1. Field of the Invention
The present invention relates to electric toothbrushes and, more particularly, is concerned with a brush head on an electric toothbrush defining a brushing plane and being supported for movement along a path of revolution having an axis extending substantially parallel to the brushing plane such that the brushing plane is maintained in the same orientation relative to a set of teeth throughout movement of the brush head along the path of revolution.
2. Description of the Prior Art
Known prior art electric toothbrushes typically include a handle, a drive unit mounted in the handle and having a drive shaft extending to an end of the handle, and a brush head rotatably supported at the end of the handle and driven via a driving linkage to the drive shaft such that a cleaning or brushing plane formed by ends of bristles of the brush head is set to undergo a rotary turning motion for cleaning a set of teeth. The typical drive unit in the handle includes an electric motor and a battery providing a source of voltage to operate the electric motor. If appropriate, the battery can be of the rechargeable type. Also, electrical switches can be provided on the handle and connected in a circuit with the electric motor and battery for switching the motor on and off.
In these known prior art electric toothbrushes, the brush head is supported for undergoing rotation about an axis extending perpendicular to the cleaning or brushing plane of the brush head. In some of these prior art electric toothbrushes, the brush head is setup to undergo an oscillatory turning motion in which the brush head swivels in one direction through a preset angle, for example of seventy degrees, and subsequently through the same preset angle in the opposite direction. In other of these prior art electric toothbrushes, the brush head is setup to undergo continuous rotation in one direction about its rotational axis extending at a right angle to the brushing plane of the brush head. A common feature of both types of brush head movements is that the bristles of the brush head are moved unevenly, since the inner bristles located adjacent to the rotational axis travel only a small distance during the turning motion of the brush head whereas the outer bristles located remote from the rotational axis travel a much greater distance. The cleaning effect of such a rotary brush head is therefore considerably greater with the bristles in its outer region than with the bristles in its inner region. In order to attain a substantially uniform cleaning effect over the entire tooth surface, the toothbrush must be moved as evenly as possible over the teeth.
In the case of toothbrushes whose brush head is driven to exert the oscillatory turning motion, the efficiency of the energy made available by the battery is lower than in such toothbrushes whose brush head carries out a rotary turning motion since, due to the reversal of the regular movement, dead points at the opposite ends of the oscillatory path must be overcome which is energy consuming.
However, in providing an electric toothbrush with a brush head which carries out a continuous rotary turning motion about a rotational axis perpendicular to the brushing plane, due to the evenness of the rotary movement the particles to be removed from the set of teeth can only be carried away with difficulty. Rather, such particles, for example food particles, press into the bristles of the brush head. In the case of the brush heads with oscillatory turning motion, through the continuous back and forth rotation of the brush head such particles can be spun or rinsed away.
Consequently, a need exists to provide an innovation in an electric toothbrush that will overcome these problems in prior art electric toothbrushes without introducing new problems in place thereof.
The present invention overcomes the aforementioned problems by providing an electric toothbrush which includes a handle, a brush head defining a brushing plane, and a guide arrangement supported by the handle and, in turn, supporting the brush head to undergo movement along an endless path of revolution having an axis of revolution extending substantially parallel to the brushing plane such that the brushing plane is maintained in the same orientation relative to a surface of a set of teeth throughout movement of the brush head along the endless path of revolution. Such brush head so provided on an electric toothbrush ensures a highly efficient utilization of the available electrical energy as well as the attainment of a more even and thus improved brushing result.
In contrast to the prior art, the brush head of the electric toothbrush of the present invention is not supported such that the brushing plane of the bristle ends remains unchanged but rather is supported such that the brush head, when driven, carries out a revolving motion in which the brushing plane with respect to its orientation relative to the surface of the teeth remains substantially unchanged. Because of the revolving motion of the brush head, all bristles of the brush head are moved evenly along the surface of the teeth to be cleaned which has not only an advantageous effect of even wear of the individual bristles but also of an even brushing.
Also through the revolving movement of the brush head and corresponding displacement of the brushing plane of the bristle ends along the endless path of revolution, the brush head, during operation of the electric toothbrush, is lifted with each revolving movement off the surface of the teeth, applied again at another site on the surface of the teeth, moved along the surface of the teeth and again lifted. This entails the advantages that a brushing movement is possible in a substantially linear direction and that through the lifting of the brush head dissolved or loosened food particles can be flushed away from the brush head by the foam of a tooth cleaning means. This cleaning or brushing movement is usefully provided, or is presettable by adjusting the direction of revolving movement of the brush head, such that the brush head is moved away from the gum tissue independently of the orientation of the toothbrush. Tooth brushing with a brush head moved in this way is especially gentle on the gum tissue.
By carrying out the revolving of the brush head in a continuous motion in one direction, the energy efficiency of an available voltage source is increased since, in contrast to brush heads with an oscillatory turning motion, no dead points need to be overcome. Consequently, the driving force is also greater such that to generate the same force a less powerful electric motor can also be used. However, in accordance with the present invention, the brush head can also usefully be provided so to additionally carry out an oscillating movement.
In one exemplary embodiment, the brush head is usefully driven by a rotary crank drive wherein the brush head itself is supported by a reciprocatory guide arrangement such that, upon being driven, the brush head carries out the desired revolving motion. A switch can be usefully disposed in the handle such that the brush head can be driven in the one as well as also in the opposite direction.
These and other features and advantages of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings wherein there is shown and described an illustrative embodiment of the invention.